Hypoxia in tumors,regarded as one of the most troublesome obstacles in cancer therapy,is responsible for the strong resistance to conventional therapy,increased invasiveness and aggressiveness,and poor prognosis in many cancer types.In this talk,I will focus on the latest progresses of our group on the UCNPs-based nanotheranostics for the imaging and therapy of hypoxic tumors.First,I can offer a thorough description of the design and engineering of hypoxia-responsive probes that can reliably image hypoxia in vitro and in vivo by noninvasive approaches[1-2].Then,I can summarize our recently developed UCNPs-based nanotheranostics which can be used for the effective treatment of hypoxic tumors [3-8],all of which help to achieve optimal treatment efficacy even for thorough eradication of solid tumors.